CN101785210B - Channel aware multiple user MIMO scheme unified with single user closed loop MIMO - Google Patents

Abstract

By receiving Level 1 CQI values from one or more user stations, the base station can make single-user MIMO schemes consistent with multi-user MIMO schemes. The base station also receives precoding vectors from the user stations and then determines which user station has the optimal Level 1 CQI value. The base station then determines the beamforming matrix to use, at least in part, based on the vectors received from the user station with the optimal Level 1 CQI value. The base station then broadcasts data to the user stations, using the beamforming matrix corresponding to the user station with the optimal Level 1 CQI value to achieve single-user MIMO in one or more streams destined for that user station, or using the beamforming matrix corresponding to the user station with the optimal Level 2 CQI value to achieve multi-user MIMO in multiple streams.

Description

A channel-aware multi-user MIMO scheme consistent with single-user closed-loop MIMO

Background technique

In recent years, a multi-user-multiple-input multiple-output (MU-MIMO) scheme is drawing more and more attention because MU-MIMO can provide multi-user diversity and space diversity. The capacity of MU-MIMO may be much higher than Single User MIMO (SU-MIMO), especially when the antenna configuration is asymmetrical, eg in a 4x2 arrangement or a 2x1 arrangement. An asymmetric configuration may occur when a base station (BS) has a larger number of transmit (Tx) antennas than the number of receive (Rx) antennas of a subscriber station (SS), or in highly correlated channel conditions. MU-MIMO differs from SU-MIMO in that MU-MIMO may involve the transmission of transport streams for multiple users in one transmission functional unit.

Description of drawings

The claimed subject matter is specifically identified and expressly claimed in the concluding portion of the specification. Such subject matter, however, can be understood by referring to the following Detailed Description when read in conjunction with the accompanying drawings, which include:

Figure 1 is a block diagram of an MU-MIMO system according to one or more embodiments;

Figure 2 is a diagram of a channel-aware MU-MIMO transmission scheme with multiple streams, according to one or more embodiments;

3 is a diagram of a MU-MIMO transmission scheme using feedback of channel quality indicators and vectors (CQI/V) without downsampling, according to one or more embodiments;

4 is a diagram of a MU-MIMO transmission scheme using feedback with downsampled channel quality indicators and vectors (CQI/V), according to one or more embodiments; and

5 is a flowchart of a method for aligning a multi-user MIMO scheme with a single-user MIMO scheme, according to one or more embodiments.

It will be appreciated that for simplicity and/or clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements.

Detailed ways

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other instances, well-known methods, procedures, components and/or circuits have not been described in detail.

In the following description and/or claims, the terms "coupled" and/or "connected" and their derivatives may be used. In particular embodiments, "connected" may be used to mean that two or more elements are in direct physical and/or electrical contact with each other. "Coupled" may mean that two or more elements are in direct physical and/or electrical contact. However, "coupled" may also mean that two or more elements may not be in direct contact with each other, but still cooperate and/or interact with each other. For example, "coupled" may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Finally, in the following description and claims, the terms "on", "overlying" and "over" may be used. "On," "overlying," and "over" may be used to mean that two or more elements are in direct physical contact with each other. However, "over" may also mean that two or more elements are not in direct contact with each other. For example, "over" may mean that one element is above another element without contacting each other, and there may be another element or elements between the two elements. Additionally, the term "and/or" may mean "and", it may mean "or", it may mean "exclusive-or", it may mean "one", it may mean "some but not all", it may mean "neither" , and/or may mean "both," although the scope of claimed subject matter is not limited in this respect. In the following description and/or claims, the terms "comprises" and "comprises" and their derivatives may be used and are intended as synonyms for each other.

Referring now to FIG. 1 , a block diagram of a MU-MIMO system according to one or more embodiments will be discussed. As shown in FIG. 1 , a MIMO system 100 may include a base station (BS) 110 and one or more of a first subscriber station (SS ₁ ), a second subscriber station (SS ₂ ) up to N subscriber stations (SS _N ) Subscriber Stations (SS) 114 , one or more of which may communicate wirelessly with base station 110 . In such a MIMO system 100 , a base station 110 may include multiple antennas 112 and a corresponding subscriber station 114 may also have one or more antennas 116 , 118 and/or 120 . It should be appreciated that one or more of the subscriber stations 114 may have its own number of antennas, wherein for example the number of antennas 116 of the first subscriber station _SS1 may be different from the number of antennas 118 of the second subscriber station _SS2 , both of which may be different from the number of antennas of the Nth subscriber station SS _N. Likewise, one or more of the subscriber stations 114 may have a different number of antennas than the base station's antennas 112, but in some cases one or more of the base stations 110 and any one or more of the subscriber stations 114 may have The same number of antennas, and the scope of claimed subject matter is not limited in this respect. It should also be noted that the model of base station 110 and subscriber station 114 shown in FIG. 1 is only an example of an arrangement for a MIMO system 100, and that in one or more alternative embodiments base station 110 may itself be subscriber station 114, and/or, for example, In an ad hoc network configuration or the like, one or more of subscriber stations 114 may communicate directly with another or more of subscriber stations 114, although the scope of claimed subject matter is not limited in this respect.

In one or more embodiments, communications between base station 110 and one or more of subscriber stations 114 may include precoding, spatial multiplexing, and/or diversity coding, alone or in combination. Furthermore, the base station 110 can communicate directly with one of the subscriber stations 114 by directing all of its antenna resources to the corresponding subscriber station 114, for example, to achieve a higher data rate, or alternatively, the base station 110 can dedicate a portion of its antenna resources to Divide among one or more subscriber stations 114 , eg, to optimize for servicing a greater number of subscriber stations 114 . In one or more embodiments to be discussed herein, MIMO system 100 may implement a channel-aware multi-user MIMO (CA-MU-MIMO) system. In such a channel-aware MIMO system 100 , the precoding vectors and/or codebook indices may be channel-aware based at least in part on feedback received from one or more users, eg, one or more of subscriber stations 114 . In one or more embodiments, a channel quality indicator (CQI) corresponding to the selected precoding vector is fed back to base station 110 for user scheduling of subscriber stations 114 in base station 110 . User scheduling in base station 110 may be based on one or more principles, such as user orthogonality or maximization of a proportional fairness metric. In one or more specific embodiments, two CQIs, such as rank-1 (Rank-1) and rank-2 (Rank-2), may be used for MIMO rank/mode adaptation. Interference unaware level 1 CQI can be used for precoding vector selection, while interference aware level 2 CQI can be used for MIMO level/link/mode adaptation and user selection. The channel-aware MU-MIMO scheme implemented by MIMO system 100 can be consistent with the single-user closed-loop MIMO scheme by using the same codebook as used in the single-user, closed-loop MIMO scheme. This MU-MIMO scheme is discussed in more detail below with respect to FIGS. 2 , 3 and 4 .

Referring now to FIG. 2 , a simplified diagram of a channel-aware MU-MIMO transmission scheme with multiple streams will be discussed in accordance with one or more embodiments. In the channel-aware MU-MIMO scheme 200 shown in FIG. 2, the transmission process that can be implemented by the base station 110 may be as follows for multiple streams, eg, in a 2×2 arrangement with two streams. It should be noted that the term 2x2 indicates that the base station 110 transmits using two antennas to the subscriber station 114 receiving using two antennas. In short, the transmission process may include a channel-aware MU-MIMO process with CQI and vector feedback. The subscriber stations 114 may perform a singular value decomposition (SVD) of all user channels in the penultimate subframe 214 of the i-th frame 212 to obtain a beamforming vector for each subscriber station 114 . Subscriber station 114 then feeds back the class 1 CQI to base station 110 . Each of the subscriber stations 114 will also feed back to the base station 110 its corresponding two principal vectors. The base station 110 then determines the selected beamforming vector, which in the 2x2 case consists of two vectors, from the subscriber station 114 with the best class 1 CQI value. The base station 110 may then broadcast the selected vector from the subscriber station 114 with the best class 1 CQI value to all subscriber stations 114 in the last subframe 216 of the ith frame 210 . Then, for the class 2 CQI feedback in the last subframe 216 of the i-th frame 210, each subscriber station calculates the class 2 CQI by using the broadcast vector received from the base station 110, which may include two class 2 CQIs in this example. Subscriber station 114 may then feed back the calculated two CQIs to base station 110 . When receiving the CQI, the base station 110 may determine the group pair user according to the scheduling standard and/or MIMO mode/level, according to the level 1/level 2 CQI received by the base station 100 from the user station 114 (Upon receipt thereof, base station 110 may determine the pairing users based on scheduling criteria and/or MIMO mode/rank according to the Rank-1/Rank-2CQIs basestation 100 received from subscriber stations 114). In level 1 mode or where the same user is allocated to both streams on the same resource block (RB), then base station 110 may choose to use single-user MIMO transmission. Otherwise, select multi-user transmission.

In one or more embodiments, a more detailed transmission process for the channel-aware MU-MIMO scheme 200 of FIG. 2 may be as follows. In the penultimate subframe 214 of the i-th frame 210, for the uplink (UL) transmission from the subscriber station 114 to the base station 110, each subscriber station 114 feeds back a grade 1 CQI value to the base station 110 according to its own channel information for grade Adaptation, SVD decomposition can be based on this channel information. In level 1 CQI calculation, there is no interference from the second stream. Each subscriber station then feeds back to the base station 110 its corresponding SVD-decomposed beamforming matrix or its two principal vectors from its own channel matrix.

Subsequently, in the last subframe 216 of the i-th frame 210, for downlink (DL) transmissions from the base station 110 to the subscriber stations 114, the base station 110 compares all received class 1 CQIs from each of the subscriber stations 114, and determines Which of the subscriber stations 114 has the best class 1 CQI value. The base station 110 may then determine the selected beamforming matrix comprising the two main beamforming vectors from the subscriber station 114 having the best class 1 CQI value. Base station 110 then broadcasts the selected beamforming matrix to all subscriber stations 114 in MIMO system 100 .

For subsequent uplink transmissions, each subscriber station then computes a level 2 CQI which may include two level 2 CQIs in the case of two streams by using beamforming matrix vectors which in this example are two vectors, and then combining the two The calculated CQI is fed back to the base station 110 . In one or more embodiments, the level 2 CQI may be calculated using an interference-aware minimum mean square error (MMSE) receiver of the subscriber station 114 . Then, each subscriber station 114 feeds back two class 2 CQI values to the base station 10 for the subscriber pair.

Subsequently, in the next frame, ie, the first subframe 218 of the (i+1)th frame 212, for downlink transmission, the base station 110 may base station 110 according to the scheduling criteria of MU-MIMO and/or according to the MIMO mode/level, according to the previous The class 1/class 2 CQI received by the subscriber station 114 is used to determine the group pair for the subscriber station 114. Base station 110 may then begin transmitting data using precoding vectors (described below). If the value of the class 1 CQI is greater than the single-user class 2 CQI and/or the multi-user class 2 CQI, the base station 110 selects the SU-MIMO class 1 mode for data transmission. In this case, the base station 110 will transmit a stream using the first vector from the broadcast beamforming matrix of the selected subscriber station 114. This selected subscriber station 114 corresponds to the highest valued class 1 CQI compared to the SU-MIMO class 2 CQI and/or the MU-MIMO class 2 CQI.

Otherwise, base station 110 selects the SU-MIMO level 2 mode for data transmission in case the single-user level 2 CQI is greater than the single-user level 1 CQI and/or the multi-user level 2 CQI. In this case, the base station 110 will employ the two vectors from the broadcast beamforming matrix of the selected subscriber station 114 to transmit the two streams. This selected subscriber station 114 corresponds to the highest valued SU level 2 CQI compared to the SU level 1 CQI and/or the MU level 2 CQI.

Otherwise, if none of the above comparisons are valid, the base station 110 selects MU-MIMO level 2 mode for data transmission. In this case, the base station 110 will transmit the two streams using the two beamforming vectors from the broadcast beamforming matrices of the selected two different subscriber stations. Based on summing two different subscriber stations 114, the two selected subscriber stations 114 will have the highest valued MU level 2 CQI compared to the SU level 1 CQI and/or the SU level 2 CQI.

In one or more embodiments, the channel-aware MU-MIMO scheme 200 shown in FIG. 2 can be extended to a larger number of streams beyond two streams and a larger number of antenna configurations, for example, where base station 110 can have 4 antennas and subscriber station 114 may have a 4x2 antenna configuration with 2 antennas, or a 4x4 antenna configuration where base station 110 may have 4 antennas and subscriber station 114 may have 4 antennas, and so on. In such extensions, differences may include the number of feedback beamforming vectors and CQIs used. With a larger number of streams/larger antenna configuration, there will be a corresponding feedback number of beamforming vectors and CQIs. For example, for the case of 4 streams configured by 4x4 antennas, for multiple users in MIMO system 100, there will be 4 beamforming vectors for broadcast and 4 CQIs for user group pairs. However, these are merely examples of how multiple streams and/or greater numbers of antennas may be implemented, and the scope of claimed subject matter is not limited in these respects.

Referring now to FIG. 3 , a diagram of a MU-MIMO transmission scheme using feedback of channel quality indicators and vectors (CQI/V) without downsampling will be discussed in accordance with one or more embodiments. In the channel-aware MU-MIMO scheme 300 of FIG. 3, downsampling is not employed at the frame level. In one specific embodiment, the frame size is 5 milliseconds, although the scope of claimed subject matter is not limited in this respect. As shown in FIG. 3 , for each subframe, each subscriber station 114 may feed back the same content to the base station 110 , for example, each subscriber station 114 will feed back a CQI value at least partly according to the latest channel information. Each subscriber station 114 will calculate two level 2 CQIs based at least in part on the broadcasted two or more beamforming vectors received from the base station 110 and then feed back the level 2 CQI to the base station 110 .

In the next subframe, the base station 110 will select two new beamforming vectors for broadcast from the subscriber station 114 with the highest valued class 1 CQI. The base station 110 will transmit data through the selected MIMO mode, SU-MIMO mode or MU-MIMO mode, and precode the data using the selected beamforming vector. In one or more embodiments, the feedback over the entire band within a subframe may be based at least in part on the best M algorithm in order to reduce feedback overhead. Beamforming vectors may also be used in conjunction with CQI feedback based at least in part on the best-M algorithm. Such an embodiment can be realized via streamlined mode. Each subframe may have the same feedback overhead, and each subframe may enable switching between SU-MIMO mode and MU-MIMO mode, between class 1 and class 2, etc., but the scope of claimed subject matter is not limited to these aspect.

Referring now to FIG. 4 , a diagram of a MU-MIMO transmission scheme using feedback with downsampled channel quality indicators and vectors (CQI/V) will be discussed in accordance with one or more embodiments. In the channel-aware MU-MIMO scheme 400 of FIG. 4, downsampling can be used for frame-level feedback. In one or more embodiments, the frame size may be 5 milliseconds or greater. The MU-MIMO scheme 400 of FIG. 4 is substantially similar to the MU-MIMO scheme 300 of FIG. 3 , where the differences may include switching units or switching periods. Each frame of 5ms or a frame longer than 5ms will feed back the same content. For example, each subscriber station 114 will feed back a CQI based at least in part on the most recent channel information. Each subscriber station 114 will compute two level 2 CQIs based at least in part on the broadcasted two beamforming vectors and then feed them back to base station 110 .

In the next 5ms frame or a longer frame longer than 5ms, the base station 110 will select two new beamforming vectors for broadcast from the subscriber station with the highest value class 1 CQI. The base station 110 will transmit the data via the selected MIMO mode, SU-MIMO or MU-MIMO, and precode the data using the selected beamforming vector. Feedback over the entire band within a frame of 5 ms or longer than 5 ms may be based at least in part on the best M algorithm in order to reduce feedback overhead. Beamforming vectors may also be used in conjunction with CQI feedback based at least in part on the best-M algorithm. This can be achieved via streamline mode. Each frame of 5ms or longer than 5ms will have the same feedback overhead, and each frame of 5ms or longer than 5ms may have Interchangeable exchanges, but the scope of claimed subject matter is not limited in these respects.

In one or more embodiments, a channel-aware MU-MIMO scheme may enable scheduling and/or hybrid automatic repeat request (HARQ) retransmission. For channel-aware MU-MIMO user scheduling, user scheduling in the base station may be based at least in part on principles such as user orthogonality or maximization of proportional fairness metrics. In user scheduling, base station 110 will compute PF metrics based at least in part on SU level 1, SU level 2 and/or MU level 2 CQIs and/or based at least in part on criteria to select a MIMO mode for transmission. User group pairs can then be determined.

For HARQ implemented in channel-aware MU-MIMO scheme, HARQ retransmission can be implemented as asynchronous mode or synchronous mode. Non-blanking/blanking HARQ mode can be used for channel-aware MU-MIMO schemes, where MU-MIMO will have two streams for transmission even if the MIMO system 100 is experiencing retransmissions. For example, in a case where two data streams are supported, where there are two streams transmitted for MU-MIMO, the one stream with error will be retransmitted at the next transmission time. Another correct stream will be delivered with the new data at the next transmission time. The precoding vector used for new data and retransmissions may be the closest beamforming vector from the MU-MIMO schedule.

In one or more embodiments of MU-MIMO, mode/level adaptation may be used to maintain link performance even when the channel is changing. Variation patterns can be implemented for flexible and/or semi-static solutions. For the flexible adaptation mode, the subscriber station will feed back the CQI values of all adaptable levels/modes, and then the base station 110 will collect all information for mode/level determination. Changes can be made on a frame-by-frame level. This change mechanism may have sufficient performance and high feedback overhead. For semi-static adaptation, the subscriber station 114 will request an adaptation when the subscriber station 114 notices a channel change, and then the base station 110 determines the required adaptation. In this arrangement, the frequency can be changed more slowly but with a smaller amount of feedback overhead.

In one or more embodiments, a channel-aware MU-MIMO scheme may utilize downlink transmissions for pilot signal measurement and/or detection. Pilots for measurements can be realized e.g. from scattered common pilots, Midamble, reference signals in order to calculate MIMO CQI feedback, e.g. Channel Quality Indicator (CQI), Control Sequence Indicator (CSI), Power Headroom Indicator (PMI), codebook index, etc. (Pilots for measurement may be implemented, for example from a scattered common pilot, a midamble, reference signals to calculate out the MIMO CQI feedback, such as channel quality indicator (CQI), control sequence indicator (CSI), power margin indicator (PMI), codebook index, and so on). Where pilots are used for demodulation, channel-aware MU-MIMO schemes can utilize dedicated precoded pilots for data detection in order to save pilot overhead, although the scope of claimed subject matter is not limited in these respects.

Referring now to FIG. 5 , a flowchart of a method for aligning a multi-user MIMO scheme with a single-user MIMO scheme will be discussed, in accordance with one or more embodiments. Method 500 of FIG. 5 includes one particular order of SU-MIMO and MU-MIMO schemes, however, method 500 may include a different order and/or more or fewer blocks than shown in FIG. 5 and the scope of claimed subject matter Not limited to this aspect. At block 510, the base station 110 receives class 1 CQI values from one or more subscriber stations 114, which may be generally referred to as users. At block 512, the base station 110 receives two or more vectors corresponding to beamforming matrix codebooks from corresponding subscriber stations. Then at block 514, the base station 110 determines which of the users has the best class 1 CQI value. Then at block 516, the base station 110 selects the vector corresponding to the user with the best class 1 CQI value. Using the vector from the user with the best class 1 CQI value, at block 518, the base station 110 broadcasts the vector to all users. The user will then calculate the level 2 CQI value by using the broadcast vector and then feed back the level 2 CQI value, which is received by the base station 110 at block 520 . Then at block 522 the base station 110 determines the user group pair based at least in part on the class 2 CQI value by comparing the class 1 and class 2 values received from the subscriber station 114 . If at block 524, the base station 110 determines that the class 1 CQI value is the best value of the CQI value, or that the same user is allocated to two or more streams, then the base station 110 selects single-user MIMO operation. Otherwise, if at block 526 the base station determines that two or more users combined have the best class 2 CQI value, then the base station 110 selects multi-user MIMO operation.

Although the claimed subject matter has been described with a certain degree of detail, it will be appreciated that elements thereof may be altered by those skilled in the art without departing from the spirit and/or scope of the claimed subject matter. We believe that the subject matter related to channel-aware multi-user MIMO schemes consistent with single-user closed-loop MIMO and/or many of its concomitants will be understood from the above description, and it will be clear that the form, construction, and Various changes in and/or arrangements without departing from the scope and/or spirit of the claimed subject matter or without sacrificing all of its material advantages, the foregoing forms herein are merely illustrative examples thereof, and/or are not intended to Substantial changes are provided. It is the intent of the claims to cover and/or include such modifications.

Claims (14)

1. method comprises:

In ul transmissions, receive grade 1 channel quality indicator values from one or more subscriber stations, described channel quality indicator values is at least part of based on channel information;

In ul transmissions, receive two or more vectors from described one or more subscriber stations;

Determine described one or more subscriber stations which have optimal level 1 channel quality indicator values;

At least part of basis is determined beam forming matrix from described two or more vectors that the described subscriber station that is defined as having described optimal level 1 channel quality indicator values receives;

In downlink transmission, to all described subscriber stations broadcasting described beam forming matrix corresponding with the described subscriber station that is defined as having described optimal level 1 CQI;

In ul transmissions, receive grade 2 channel quality indicator values from described one or more subscriber stations;

If grade 1 channel quality indicator values is greater than from described grade 2 channel quality indicator values of single subscriber station or greater than described grade 2 channel quality indicator values from a plurality of subscriber stations, then:

Select alone family multiple-input and multiple-output grade 1 pattern for transfer of data; And.

Grade 1 vector that forms with the wave beam corresponding with the described subscriber station with described optimal level 1 channel quality indicator values transmits a data flow.

2. the method for claim 1 also comprises:

In ul transmissions, receive described grade 2 channel quality indicator values from described one or more subscriber stations;

If from grade 2 channel quality indicator values of single subscriber station greater than from grade 1 channel quality indicator values of single subscriber station or greater than grade 2 channel quality indicator values from a plurality of subscriber stations, then:

Select alone family multiple-input and multiple-output grade 2 patterns for transfer of data; And

Described beam forming matrix with the described subscriber station with optimal level 2 channel quality indicator values transmits two data flow.

3. the method for claim 1 also comprises:

In ul transmissions, receive described grade 2 channel quality indicator values from described one or more subscriber stations;

If two or more subscriber stations have optimal level 2 channel quality indicator values, then:

Select multi-user's multiple-input and multiple-output grade 2 patterns for transfer of data; And

Described beam forming matrix with described two or more subscriber stations with described optimal level 2 channel quality indicator values transmits two data flow.

4. the method for claim 1, wherein described channel quality indicator values is at least part of based on singular value decomposition.

5. the method for claim 1, wherein described channel quality indicator values is at least part of based on not having noisy hypothesis between two or more streams.

6. the method for claim 1, wherein describedly receive grade 1 channel quality indicator values and describedly receive grade 2 channel quality indicator values from described one or more subscriber stations and carry out in each subframe from one or more subscriber stations.

7. the method for claim 1, wherein, describedly receive grade 1 channel quality indicator values and describedly receive at least part of the calculating according to best M of grade 2 channel quality indicator values from described one or more subscriber stations and carry out in each subframe from one or more subscriber stations, in order to reduce feedback overhead from described one or more users.

8. equipment comprises:

Be used at the parts of ul transmissions from one or more subscriber stations reception grade 1 channel quality indicator values, described channel quality indicator values is at least part of based on channel information;

Be used for receiving from described one or more subscriber stations in ul transmissions the parts of two or more vectors;

Be used for to determine described one or more subscriber stations which have the parts of optimal level 1 channel quality indicator values;

Be used for described two or more vectors that at least part of basis receives from the described subscriber station that is defined as having described optimal level 1 channel quality indicator values and determine the parts of beam forming matrix;

Be used at the parts of downlink transmission to all described subscriber stations broadcasting described beam forming matrix corresponding with the described subscriber station that is defined as having described optimal level 1 CQI;

Be used for receiving from described one or more subscriber stations in ul transmissions the parts of grade 2 channel quality indicator values;

If be used for grade 1 channel quality indicator values greater than from described grade 2 channel quality indicator values of single subscriber station or greater than described grade 2 channel quality indicator values from a plurality of subscriber stations, then carry out the parts of following operation:

Select alone family multiple-input and multiple-output grade 1 pattern for transfer of data; And

Grade 1 vector that forms with the wave beam corresponding with the described subscriber station with described optimal level 1 channel quality indicator values transmits a data flow.

9. equipment as claimed in claim 8 also comprises:

Be used for receiving from described one or more subscriber stations in ul transmissions the parts of described grade 2 channel quality indicator values;

Then carry out the parts of following operation if be used for from grade 2 channel quality indicator values of single subscriber station greater than from grade 1 channel quality indicator values of single subscriber station or greater than grade 2 channel quality indicator values from a plurality of subscriber stations:

Select alone family multiple-input and multiple-output grade 2 patterns for transfer of data; And

Described beam forming matrix with the described subscriber station with optimal level 2 channel quality indicator values transmits two data flow.

10. equipment as claimed in claim 8 also comprises:

Be used for receiving from described one or more subscriber stations in ul transmissions the parts of described grade 2 channel quality indicator values;

Have optimal level 2 channel quality indicator values if be used for two or more subscriber stations, then carry out the parts of following operation:

Select multi-user's multiple-input and multiple-output grade 2 patterns for transfer of data; And

Described beam forming matrix with described two or more subscriber stations with described optimal level 2 channel quality indicator values transmits two data flow.

11. equipment as claimed in claim 8, wherein, described channel quality indicator values is at least part of based on singular value decomposition.

12. equipment as claimed in claim 8, wherein, described channel quality indicator values is at least part of based on not having noisy hypothesis between two or more streams.

13. equipment as claimed in claim 8 wherein, describedly receives grade 1 channel quality indicator values and describedly receives grade 2 channel quality indicator values from described one or more subscriber stations and carry out in each subframe from one or more subscriber stations.

14. equipment as claimed in claim 8, wherein, describedly receive grade 1 channel quality indicator values and describedly receive at least part of the calculating according to best M of grade 2 channel quality indicator values from described one or more subscriber stations and carry out in each subframe from one or more subscriber stations, in order to reduce feedback overhead from described one or more users.

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